Biogas is produced by the anaerobic digestion of organic materials including crop and forest residues, sewage sludge, and agricultural waste. Biogas consists of CH4, CO2, and trace amounts of moisture, NH3, H2S, etc. Biogas could be burned directly to generate heat or power, but this combustion process has a low efficiency (i.e. low calorific value) due to the presence of CO2 and H2O. Biogas could be utilized to produce syngas (H2 and CO) via reforming technology followed by Fischer-Tropsch Synthesis (FTS) to produce higher value products.1, 2 There is also interest in tri-reforming as a means for CO2 sequestration.3, 4 
There are several main reforming technologies to convert biogas to syngas without the removal of CO2 including dry reforming (reaction (1)), bi-reforming (reaction (1) and reaction (2)), and tri-reforming (reaction (1), reaction (2), and reaction (3)). Bi-reforming of methane has the advantage of producing 2:1 H2/CO syngas that could be directly converted into high value products. However, a major problem during the bi-reforming process is carbon deposition that can deactivate the catalyst.2 Tri-reforming of methane is a combination of dry reforming, steam reforming and partial oxygen reforming, where O2 and H2O decrease the carbon deposition on the catalyst. The major reactions during the tri-reforming process are shown below. In addition, the molar ratio of H2 to CO during the tri-reforming process could be controlled to achieve an optimum value. The partial oxidation reaction relieves some heat duty from the reactor.5-7CH4+CO2=>2CO+2H2 ΔH○=247.3 kJ/mol  (1)CH4+H2O=>CO+3H2 ΔH○=206.3 kJ/mol  (2)CH4+½O2=>CO+2H2 ΔH○=−35.6 kJ/mol  (3)CO+H2O=>CO2+H2 ΔH○=−41.1 kJ/mol  (4)CH4=>C+2H2 ΔH○=74.9 kJ/mol  (5)2CO=>C+CO2 ΔH○=−172.2 kJ/mol  (6)C+O2=>CO2 ΔH○=−393.7 kJ/mol  (7)C+H2O=>CO+H2 ΔH○=131.4 kJ/mol  (8)
Tri-reforming of methane requires a high reaction temperature of approximately 800-1000° C. due to the typical net endothermic nature of the reactions, causing many catalysts to deactivate over relatively short period of times. This has led to a need for tri-reforming catalysts that are thermally stable and resistant to coke deposition2. Ni-based catalysts have been proven to show good catalytic performance towards methane reforming. Nickel is cheap and easy accessible; however, Ni-based catalysts deactivate gradually. Redox support materials such as CeO2 and (Ce,Zr)O2 could reduce carbon deposition and prevent metal sintering due to high oxygen storage capability and strong metal-support interaction. Moreover, magnesia could help reduce the carbon deposition.5, 8 
Pressure drop and mass transfer efficiency are two potential/additional limiting factors in commercial processes.9 Most research level experiments are done on the powder form of catalyst to maximize mass transfer efficiency but these powder forms of the catalyst are not typically applicable in a fixed bed commercial reactor largely due to the extreme pressure drops that would be encountered. However, formed catalysts with various shapes can be optimized to balance transport limitations vs pressure drop effects. Extrudate catalysts have been developed for steam reforming of methane on the industrial scale. Coke formation and energy requirements are major challenges, especially at typical industrially used pressures.10 Many researchers have investigated methane reforming under atmospheric pressure due to cost and safety concerns. However, this will adversely affect the process economics since syngas must be pressurized for downstream processing such as Fischer-Tropsch Synthesis.11 New research level advancements in catalyst support materials and formulations offer the ability to overcome traditional commercial scale limitations but must be modified to meet the demanding physical conditions of large scale applications. Therefore, Ni-based formed catalysts with optimized formulations for tri-reforming of methane at higher pressures (e.g. >3 bar) are worth exploring.
Although literature studies of methane reforming are primarily on powder catalysts, formed catalysts—including foam, ceramic monolith, pellet, bead, sphere, and tablet—have been the focus of recent research. For example, Roy et al.12 investigated the steam reforming of a model biogas (60% CH4 and 40% CO2) over PdRh/CeZrO2/Al2O3/metal foam catalysts at 1 atm in a tubular fixed-bed reactor. The PdRh clusters supported on CeZrO2-modified Al2O3 powder were coated on a Ni—Cr—Al alloy foam substrate to form the catalyst. With a steam to CH4 ratio of 1.5 and the gas hourly space velocity (GHSV) of 20,000 h−1, CH4 conversion increased from 62% to around 99% and the CO2 conversion increased from −21% to 18% with increasing reaction temperatures from 650° C. to 850° C. However, the H2/CO molar ratio decreased with increasing reaction temperatures. Alumina pellets modified with a NiMg/CeZrO2 were tested in our previous biogas tri-reforming studies, but the GHSV (<3,000 h−1) was low in comparison to what is needed at the pilot and commercial scales.13 Vita et al14 studied the oxy-steam reforming of methane over Ni/CeO2 loaded cordierite monolith catalysts at 1 atm in a fixed-bed quartz reactor. The monolith catalysts were synthesized through a combination of solution combustion synthesis and wet impregnation. The CH4/H2O/O2 molar ratio was 1:1.2:0.55, weight hourly space velocity (WHSV) was 65,000 NmL/(gcat*h), and the reaction temperature was 500-800° C. CH4 conversion increased and H2/CO molar ratio decreased with increasing reaction temperature. Garcia-Vargas et al.15 studied the tri-reforming of methane over NiMg/SiC pellet catalysts at 1 atm in a tubular quartz reactor. The NiMg/SiC pellet catalysts were synthesized through the impregnation method using SiC pellet (radius was 0.5 mm, purchased from SCAT CATALYST company) as the support. The WHSV was 60,000 NmL/(gcat*h) and the reaction temperature was 407-800° C. The H2/CO molar ratio (varying between 1.1 and 3.1 at 737° C.) was affected by the feed gas composition. CO2 conversion decreased as the concentration of H2O and O2 increased. To this point, biogas tri-reforming over formed catalysts at pressures higher than 1 atm have not been reported in the literature. This is attributed to the difficulty in producing a formed catalyst that is stable at the high pressures and temperatures needed.
There remains a need for improved catalysts that overcome the aforementioned deficiencies. Mixed oxide supports offer advantages over single metal oxide support materials with respect to desired tri-reforming catalyst performance but also present unique challenges to incorporate the mixed oxides into the desired form capable of withstanding commercial scale reactor conditions while overcoming pressure drop limitations and maintaining desired conversions with long catalyst lifetimes.